Non-radio-interfering therapeutic apparatus



March 17, 1942. A. s. M -lN w K 2,276,996

NON-RADIO-INTERFEHING THERAPEUTIC APPARATUS Filed Nov. 30, 1940 2Sheets-Sheet 1 INVENTOR fl.-$'. N/L/JVOWSKI.

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ATTORNEY March 17, 1942. A. s. MILINOWSKI 2,276,996

NON-RADIO-INTERFERING THERAPEUTIC APPARATUS Filed Ndv. so. 1940 2Sheets-Sheet 2 ATTORNEY Patented Mar. 17, 194 2 STAT PATE orriceNON-RADIO-INTERFERING THERAPEUTIC APPARATUS Arthur S. Milinowski, NewYork, N. assignor to A. J. Ginsberg, New York, N. Y.

Application November 30,}940, Serial No. 367,895 a 18 Claims.

The invention relates to short wave apparatus and especially to shortwave diathermy apparatus. An object of the invention is to minimize theradiations from a short wave apparatus that v the portion of theapparatus directly applied to the patient.

A still further object of the invention is to confine the particularparts producing interfering radiations to the casing applied to thepatient in order to eliminate expensive shielding that would otherwisebe necessary to effectively shield the apparatus.

Other objects and advantages of the invention will be apparent from thefollowing description and drawings wherein:

Fig. 1 is a perspective view of a completed commercial embodimentof theinvention.

Fig. 2 is a cross section on lines IIII of Fig. 1.

Figs. 3 and 4, respectively, are cross sections on lines III--III andIV--IV of Fig. 2.

Fig. 5 is a diagrammatical view of the preferred circuit arrangement ofthe apparatus.

Fig. 6 is a front view of a screen that may be utilized in theapparatus. In some respects this application is a. continuation-impartof my copending application on Electrotherapy, Ser. No. 186,329, filedJanuary 22,

1938. The use of short wave diathermy apparatus such as described inthis copending application ordinarily gives rise to strongelectromagnetic radiations which cause radio interference. It isexceedingly d fllcult to eliminate these radiations. The patient orapplicator circuit generally comprises in part a large loop or coilwhich is tuned to greatest current flow and becomes an effectiveantenna. A certain amount of high frequency current gets to the powerline and cannot be'kept out by ordinary filter means, The use of part ofthe circuit to act with any efliciency as a radiator. I

In Fig. 1 I have disclosed the usual control panel Ill-mounted on aportable cabinet II with a connection l2 to a suitable source of powersupplying 750 to 3000 volts. This panel l0 contains the well knownswitch I3, adjustments l4, and meters l5. From this panel and cabinetextend two arms l6 and H. These arms, as disclosed in Fig. 3, containanode lead l8 and two cathode leads Hand 20. These leads are thepreferably minimum number which can be used in the arrangement.

I also preferablyhav'e in these arms, close to the treatment head,filters or high frequency chokes 2| and 22. These chokes, of course,contain the condensers 23 and resistances 24 of proper design,illustrated diagrammatically in Fig. 5. I also preferably wind the plateand filament leads on tubes 25 of insulation containing iron filings 26.The iron losses are very high at the frequencies utilized, and the highfrequency currents are quickly damped out While no appreciable lowfrequency impedance is added to the circuit.

The winding of the leads on the tubes can be shunted by resistors ofproper value. A bracket 21 is connected to these arms and supports ahead 28 with a central extending circular flange 29 through which thecurrent leads extend. On this flange is a plate 30 towhich is securedthe casing 3| constituting the treatment head. This casing is attachedby a screw-threaded plate 32, and

a washer 33 intermediate the plate 30 and the head 28 allows theadjustment of the treatment head to any angle desired.

The treatment head includes a thermionic vacuum tube 35 for producinghigh frequency oscillations. This tube may be of the particular designdisclosed on the drawings or may be of any other form adapted for theproduction of high frequency oscillations. The tube, of course, containsthe anode 36, grid 31, and cathode 38; The cathode 38 is, of course,connected to the cathode leads l9 and 20. The grid 31 is connected to agrid tuning coil 39 which is connected to the easing 3| of the treatmenthead, preferably through a grid limiting resistor 40 in parallel with agrid blocking condenser 4|. The casing 3| is grounded in turn throughthe current leads I!) and 20.

The tube 35 will always be maintained in an upright position by thebracket members, and the plane of the filament is preferably the centralplane through the front and back of the casing. At the rear of thecasing 3|, as illustrated in Fig. 2, is a circular metal flange 42 andinside of this flange is supported a small fan motor 43 with a metalblade 44 of maximum diameter to just clear the flange 42. This motor isconnected to the current leads l9 and 20, as diagrammaticallyillustrated in Fig. 5. The casing 3| of the treatment head preferablyhas a double circular wall attached to the backv portion 45 thatsupports the fan motor. This double wall comprises anouter wall 45serving a a continuation of the back wall, as illustrated at 45. Theback wall has a circular flange 41 extending a short way into theinterior of the casing. A second cylindrical wall 48 is spaced slightlyfrom the outer cylindrical wall 46 and terminates intermediate theflange 41 of the back wall and the outer circular casing 46.

The outer wall 46 has a plurality of openings 49 around itscircumference to act a an intake of cooling air. The air is drawn in andpasses around the inner wall 48 to be drawn over the surface of theparts contained within the head. It will be noted in Fig. 4 that thediameter of the outer wall 46 and inner wall 48 are just sumcient' toclear the tube 35 located therein. The other parts are located about thetube so as not to increase the diameter of the casing over thatnecessitated by the tube 35.

The oscillating tank circuit connected to the tube 35 preferablycomprises a coil 50 preferably in the form of a helical hollow tube,illustrated in cross section in Fig. 2 and in elevation in Fig. 3. Oneend of this coil is connected to the plate 35 of the tube. The other endof the coil is connected to the tank condenser which is in turnconnected to the lead 52 connected from the plate to the first-mentionedend of the coil. The mid-point 53 of the oscillating tank coil 50 isconnected by an extension 54 .to the plate current lead l8 extendingthrough one of the arms l6. This lead 54 may be by-passed by a condenser55 to thecasing 3|. The tank condenser 5| preferably compnises a boltand spacers 56 attached to the outer end of the helical oscillatingcoil'illustrated in Fig. 3, and has a plurality of large plates 51extending therefrom. Interleaved with these plates 5! are other plates58 connected to another bolt and spacers 59 which has a connection 60 tothe other end SI of the oscillating tank coil; A suitable insulatorsupport 52 for the condenser secures the condenser at 63 to theremainder of the casing. The oscillating tank coil is in the front ofthe treatment head just back of an insulating front face 55. A micaplate 65 preferably extends across the treatment head between the coil50 and the remaining parts of the treatment head so that the current ofair drawn in through the ports 49 will be effectively directed overthese parts and out through the flange 42 at the rear of the treatmenthead. In

place of mica. a mica composition, such as that sold under the tradename Micalex, or other heat-resisting insulation may be used. Justinside the front portion of the casing is a grounding loop, ring, orshield 61 which is, of course, connected to the metal casing 3| asdiagrammatically illustrated in Fig. 5. While the insulating plate orface is illustrated as fiat, it may be bowed or otherwise caused to fitportions of the patient.

The coupling to the patient may be electrostatic by making use of asmall electrode plate in the front of the head, or electromagnetic bymaking direct use of the tank coil 50, or by making a combination ofboth electrostatic and magnetic. I prefer, however, to useelectromagnetic exclusively by applying the treatment head 3| directlyto the patient, preferably within one inch of the patients body portionto be treated. A

Faraday screen 68 illustrated in Fig. 6 may be used inside the frontguard between the coil 50 and the patient in place of the loop 51. Thisscreen consists of a number of wires interconnected and kept at virtualground potential, but

so arranged that there is no complete conducting loop. This screenprevents any electrostatic coupling of the patient, but permits fullelectromagnetic coupling to the oscillator coil. The virtual ground isobtained by interconnecting the screen with other metal shielding parts,all of which are connected either directly or through a blockingcondenser with the neutral point of the oscillating circuit.

The only remaining practical source of radiation is the oscillating tankcoil 50 itself. This coil preferably has a total diameter between 2 and12 inches and preferably 7 inches, which is an extremely small fractionof half a wavelength. The wavelengths generally utilized are from 6 to24 meters, so that the radiation from this oscillating tank coil is verysmall. The diameter of the coil is less than 10% at least of a halfwavelength and preferably is considerably less than this. The ratio ofthe maximum diameter of the coil' to a half wave length of theparticular frequency employed should be kept below 1 to 10. In myparticular construction the maximum length or diameter of the treatmenthead is less than 10% of half a wave length. The use of a conductingring 61 or the Faraday shield 55.

properly placed in a plane parallel to the coil is eifective in reducingradiation from thi source. It will be noted that the arrangement insidethe treatment head with the open tank condenser 5| and the grid tuningcoil 39 with its large spaced turns, as well as the effective directionof a cooling air current over these parts especially to the glasscontainer of the vacuum tube 35, provides effective cooling of thevarious portions of the circuit and increases the efiiciency' of theapparatus.

Because of the concentration of the electromagnetic field to a confinedarea of the patient. the energy is also eifectively utilized. It willalso be appreciated that the arrangement permits flexibility intreatment to a degree not hitherto possible inasmuch as it is notnecessary to keep high frequency leads away from metal and other partsof the patients body. Since the losses are extremely low, it is possibleto get an accurate indication of the wattage input to the patient ordosage by the use of a watt meter properly calibrated and compensatedfor the condition of zero load in the patient circuit.

While I have disclosed the metal parts 45 and 48 as outer parts of thecasing, the parts may be enclosed, in turn, by other material fordecorative or protective purposes. The particular bracket connectionsbetween the treatment head and cabinet may be modified from that shown.

It is apparent that many other modifications may be made in theparticular elements in regard to their number, form and arrangement, andaccordingly I desire only such limitations to be placed upon myinvention as are necessitated by the spirit and scope of the followingclaims. I

- trical energy, an arm extending from said cabinet, a treatment'headsupported by said arm, conductors extending along said arm for supplyingenergy from said source to said treatment head, means associated withsaid conductors to prevent the transmission of radio frequencies by saidconductors, an oscillating circuit in said treatment head connected tothe conductors extending from said source, said oscillating circuitincluding a vacuum tube generator. of short waves, an oscillating coiland condenser, and said treatment head being shielded to prevent theemanation of radiations of radio frequency therefrom but enabling saidradiations to be applied to a patient when inductively coupled to saidtreatment head.

2. A short wave diathermy apparatus shielded to prevent radiointerference comprising a cabinet, connections in said cabinet for.asource of electrical energy to supply high potential electrical energy,an arm extending from said cabinet, a treatment head supported by saidarm, conductors extending along said arm for supplying energy from saidsource to said treatment head, means associated with said conductors toprevent the transmission of radio frequencies by said conductors, anoscillating circuit in said treatment head connected to the conductorsextending from said source, said oscillating circuit including a vacuumtube generator of short waves, an oscillating coil and condenser, andsaid treatment head being shielded to prevent the emanation ofradiations of radio frequency therefrom but enabling said radiations tobe applied to a patient when inductively coupled to said treatment head,the maximum length of said treatment head being less than ten percent ofa half wave length of the waves produced by said oscillating circuit.

3. A short wave diathermy apparatus shielded to prevent radiointerference comprising a cab inet, connections in said cabinet fora'source of electrical energy to supply high potential electricalenergy, an armextending from said cabinet, a treatment head supported bysaid arm, conductors extending along said arm for supplying energy fromsaid source to said treatment head, means associated with saidconductors to prevent the transmission of radio fre-.

quencies by said conductors, an oscillating circult in said treatmenthead connected to the conductors extending from said source, saidoscillating circuit including a vacuum tube generator of short waves, anoscillating coil and condenser, the maximum diameter of said oscillatingcoil being less than ten percent of half a wave length of the wavesproduced by said oscillating circuit, and said treatment head beingshielded to prevent the emanation of radiations of radio frequencytherefrom but enabling said radiations to be applied to a patient wheninductively coupled to said treatment head.

4. A treatment head for short wave diathermy apparatus comprising asmall portable metallic casing containing an oscillating circuitincluding a vacuum tube generator of short waves, and an oscillatingcoil and condenser, metallic shielding means grounded with respecttosaid casing, said casing and shielding means cooperating as asubstantially complete shield on all sides except the portion adjacentthe oscillating coil applied to the patient.

5. A treatment head forshort wave diathermy apparatus, comprising asmall portable casing containing an oscillating circuit including a 78*vacuum tube generator of short waves, an oscillating coil and condenser,said casing having a front portion permitting radiant energy to pass tothe patient, a rear portion of metal with an opening therein, a metalfan blade extending substantially across said opening, a fan motorsupported on said casing, openings in the remaining portions of saidcasing, and means within the casing shielding said openings.

6. A treatment head for short wave diathermy,

comprising a small portable, casing having en-- closure forming walls ofwhich one comprises a front face portion of insulation for applicationtowards the patient, anoscillating coil directly back of said frontface, a vacuum tube generator of short waves and a condenser within saidcasing connected with said oscillating coil, the remaining walls of saidcasing being metallic and shielding the oscillating coil, generator andcondenser.

7. A treatment head for short wave diathermy,

comprising a small portable casing having enclosure forming walls ofwhich one comprises'a front face portion ofinsulation for applicationtowards the patient, an oscillating coil directly back of said frontface, a vacuum tube'generator of short waves and a condenser within saidcasing connected with said oscillating coil, the remaining walls of saidcasing being metallic and shielding the oscillating coil, generator andcondenser, the maximum diameter of said oscillating coil being less thanten percent of half a wave length of the waves produced in said coil bysaid generator.

8. Atreatment head for short wave diathermy comprising a small portablecasing having enclosure forming walls of which one comprises a frontface portion of-insulation for application towards the patient, anoscillating coil directly back of said front face, a vacuum tubegenerator of short waves and a condenser within said casing connectedwith said oscillating coil, the remaining walls of said casing beinmetallic and shielding the oscillating coil, generator and condenser,said casing being perforated and a fan supported on said casing forcooling the elements in said casing.

9. A treatment head for short wave diathermy comprising a small portablecasing having enclosure forming walls of which one comprises a frontface portion of insulation for application towards the patient, anoscillating coil directly back of said front face, a vacuum tubegenerator of short waves and a condenser within said casing connectedwith said oscillating coil, the remaining walls of said casing beingmetallic and shielding the oscillating coil, generator and condenser,said casing being perforated and a fan supported on said casing forcooling the elements in said casing, the overall dimension of said coilbeing less than half a wave length of said short waves.

10. A treatment head for short wave diathermy comprising a casing havingone face portion of insulation adapted to be applied towards a patient,an oscillating coil directly back of said face portion of insulation, ashield about said oscillating coil, the remaining portion of said casingbeing of metal and connected to said shield, a vacuum tube generator ofshort waves said cathode energization circuit and said shield.

11. A treatment head for shortwave diathermy comprising a casing havingone face portion of insulation adapted to be applied towards a patient,an oscillating coil directly back of said face portion of insulation, ashield about said oscillatingv coil, the remaining portion of saidcasing being of metal and connected to said shield, a vacuum tubegenerator of short waves having an anode, cathode and grid within saidcasing, the anode of said tube being connected to said oscillating coil,the grid of said tube being connected to said shield, an energizingcircuit for said cathode, and a filter interconnecting said cathodeenergization circuit and said shield,

the overall dimension of said oscillating coil being considerably lessthan half a wave length of. said short waves.

12. A treatment head for short wave diathermy comprising a casing havingone face of insulation adapted to be applied towards a patient, ahelical oscillating coil directly back of said face of insulation, ashield in a planeparallel with and about said coil, a generatingoscillating cirouit of short waves in said casing connected to saidcoil, a blocking condenser, said shield being connected through saidblocking condenser to said oscillating circuit, the major part of saidcasing being of metal connected to' said shield.

13. A treatment head for short wave diathermy, comprising a casinghaving one face of insulation adapted to be applied towards a pa- 1tientya helical oscillating coil directly back of said face ofinsulation, a shield in a plane parallel with and about said coil, agenerating oscillating circuit of short waves in said casing connectedto said coil, a blocking condenser, said shield being connected throughsaid blocking condenser to said oscillating circuit, the major part ofsaid casing being of metal connected to said shield, the overalldiameter of said helical oscillating coil being less than half a wavelength of said oscillating circuit.

14. A treatment head for short wave diathermy, comprising a vacuum tubeoscillator, a

cylindrical casing slightly larger in diameter than the length of saidvacuum tube oscillator surrounding said tube, said casing having a faceof insulation adapted to be applied toward a patient, a helical coilbeing located intermediate said rounding said tube, said casing having aface of.

insulation adapted to be applied towards a patient, a helical coil beinglocated between said face and said vacuum tube oscillator,'an .openplate condenser connecting the ends of said coil, said coil andcondenser being connected to said vacuum tube oscillator, thecylindrical side of said casing being of metal having openingstherethrough, and a fan supported by said casing for drawing cooling airover said vacuum tube oscillator.

16. A treatment head for short wave diathermy comprising a vacuum tubeoscillator, a cylindrical casing slightly larger in diameter than thelength of said vacuum tube oscillator surrounding said tube, said casinghaving a side of insulation adapted to be applied towards a patient, ahelical coil being located between said side and said vacuum tubeoscillator, an open plate condenser connecting the ends of said coil,said coil and condenser being connected to said vacuum tube oscillator,a shielding'member supported on the inner side of said side ofinsulation about said oscillating coil, the remaining portion of saidcasing being substantially of metal connected to said shielding member.

17. A treatment head for short wave diathermy comprising a vacuum tubeoscillator, a cylindrical casing slightly larger in diameter than thelength of said vacuum tube oscillator surrounding said tube, said casinghaving a side of insulation adapted to be applied towards a patient, ahelical coil being located intermediate said side and said vacuum tubeoscillator, an open plate condenser connecting the ends of said coil,said coil and condenser being connected to said vacuum tube oscillator,a shielding member supported on the inner side of said side ofinsulation about said oscillating coil, the remaining portion of saidcasing being substantially of metal connected to said shielding member,a blocking condenser, said shielding member being connected through saidblocking condenser to the oscillating circuit including said coil,condenser and vacuum tube oscillator.

18.'A treatment head for short wave diathermy containing a vacuum tubeoscillator having plate, cathode and grid, a helical coil and acondenser connecting the ends of said coil and forming an oscillatingcircuit connected to the plate of-said tube, a shield in said headdirecting the radiant energy from said oscillating circuit in thedesired direction, a filter interconnecting the grid of said tube andsaid shield,a cathode energization circuit for said tube, a secondfilter connecting saidenergization circuit and said shield and a leadfor supplying plate energy connected to an intermediate point on saidhelical coil.

ARTHUR S. MILINOWSKI.

